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A Genome-Wide Screen Identifies Genes in Rhizosphere-Associated Pseudomonas Required to Evade Plant Defenses.
Liu, Zhexian; Beskrovnaya, Polina; Melnyk, Ryan A; Hossain, Sarzana S; Khorasani, Sophie; O'Sullivan, Lucy R; Wiesmann, Christina L; Bush, Jen; Richard, Joël D; Haney, Cara H.
Afiliación
  • Liu Z; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada.
  • Beskrovnaya P; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada.
  • Melnyk RA; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada.
  • Hossain SS; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada.
  • Khorasani S; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA.
  • O'Sullivan LR; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA.
  • Wiesmann CL; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada.
  • Bush J; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA.
  • Richard JD; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada.
  • Haney CH; Department of Microbiology and Immunology, The University of British Columbia, Vancouver, Canada cara.haney@msl.ubc.ca.
mBio ; 9(6)2018 11 06.
Article en En | MEDLINE | ID: mdl-30401768
Pseudomonas fluorescens and related plant root ("rhizosphere")-associated species contribute to plant health by modulating defenses and facilitating nutrient uptake. To identify bacterial fitness determinants in the rhizosphere of the model plant Arabidopsis thaliana, we performed a high-throughput transposon sequencing (Tn-Seq) screen using the biocontrol and growth-promoting strain Pseudomonas sp. WCS365. The screen, which was performed in parallel on wild-type and immunocompromised Arabidopsis plants, identified 231 genes that increased fitness in the rhizosphere of wild-type plants. A subset of these genes decreased fitness in the rhizosphere of immunocompromised plants. We hypothesized that these genes might be involved in avoiding plant defenses and verified 7 Pseudomonas sp. WCS365 candidate genes by generating clean deletions. We found that two of these deletion mutants, ΔmorA (encoding a putative diguanylate cyclase/phosphodiesterase) and ΔspuC (encoding a putrescine aminotransferase), formed enhanced biofilms and inhibited plant growth. We found that mutants ΔspuC and ΔmorA induced pattern-triggered immunity (PTI) as measured by induction of an Arabidopsis PTI reporter and FLS2/BAK1-dependent inhibition of plant growth. We show that MorA acts as a phosphodiesterase to inhibit biofilm formation, suggesting a possible role in biofilm dispersal. We found that both putrescine and its precursor arginine promote biofilm formation that is enhanced in the ΔspuC mutant, which cannot break down putrescine, suggesting that putrescine might serve as a signaling molecule in the rhizosphere. Collectively, this work identified novel bacterial factors required to evade plant defenses in the rhizosphere.IMPORTANCE While rhizosphere bacteria hold the potential to improve plant health and fitness, little is known about the bacterial genes required to evade host immunity. Using a model system consisting of Arabidopsis and a beneficial Pseudomonas sp. isolate, we identified bacterial genes required for both rhizosphere fitness and for evading host immune responses. This work advances our understanding of how evasion of host defenses contributes to survival in the rhizosphere.
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Texto completo: 1 Bases de datos: MEDLINE Asunto principal: Pseudomonas fluorescens / Genoma Bacteriano / Arabidopsis / Rizosfera Tipo de estudio: Prognostic_studies / Risk_factors_studies Idioma: En Revista: MBio Año: 2018 Tipo del documento: Article País de afiliación: Canadá

Texto completo: 1 Bases de datos: MEDLINE Asunto principal: Pseudomonas fluorescens / Genoma Bacteriano / Arabidopsis / Rizosfera Tipo de estudio: Prognostic_studies / Risk_factors_studies Idioma: En Revista: MBio Año: 2018 Tipo del documento: Article País de afiliación: Canadá